New Observations of the Non-Thermal Continuum Radiation at the Plasmapause

The non-thermal continuum radiation is an electromagnetic emission associated with the plasmapause and is an important feature of the coupled inner magnetosphere. It is now believed that there are three main types of non-thermal continuum radiation that are distinguished by their frequency range and source location. The normal continuum radiation (also referred to as the trapped and escaping continuum) is typically in the 5 to 100 kHz frequency range. The continuum enhancement is observed from 10-100 kHz frequency range coming from night-side source regions. Kilometric continuum is observed to be generated at the plasmapause, in the magnetic equator, deep in notch structures of the plasmasphere over a frequency range from 100 to 800 kHz. New observations of the normal non-thermal continuum from the IMAGE/RPI instrument show a distinct "Christmas-tree" pattern in the frequency-time spectrogram that extend from 10's of Hz into the kilometric continuum frequency range (300 kHz). These observations show source region at nearly all local times. New observations of the continuum enhancement shows that the emission is associated with night-side electron injections and results in a very broad emission cone extending in frequency up to 300 kHz. These new observations of NTC will be put in the context of their role in the coupling of the hot and cold plasma populations at the plasmapause as an inner magnetospheric response to geomagnetic storms.